Slamming indicator system for marine devices

ABSTRACT

In order to detect the existence of slamming conditions in ocean going vessels a slamming indicator is provided with monitors the water pressure beneath the forefoot of the vessel and which energizes an indicator according to such pressure.

United States Patent Clay 1 June 20, 1972 [54] SLAMMING INDICATOR SYSTEMFOR MARINE DEVICES [56] References Cited [72] Inventor: John ArmstrongClay, Bowdon, England UNITED STATES PATENTS 1 Assignefi ManchesterLiners Limited, of 1,398,792 11/1921 Paulin ..200/83 Manchester- England2,695,585 11/1954 Montrose-Oster ..114/122 [22] Filed: March I3, 1970Primary Examiner-John W. Caldwell [21] P 19,452 AssistantE.\'aminerDaniel Myer A!torneyShoemaker & Mattare [30] ForeignApplication Priority Data March 15, 1969 Great Britain ..l3,7l4/69 [57]ABSTRACT In order to detect the existence of slamming conditions in [52]U.S.Cl ..340/240, 73/389, 73/406, ocean going vessels a slammingindicator is provided with 1 L R monitors the water pressure beneath theforefoot of the vessel [51 Int. Cl. ..G08b 23/00 d hi h energizes anindicator according to such pressure. [58] Field of Search ..340/236,240, 244; 73/304,

15 Claims, 8 Drawing Figures PATENTEDJUHZO m2 3. 67 1 .954

sum 1 or a F IK I 1 n I H '1 i 4 FIG. 2.

INVENTOR:

JOHN QEMsr/cw/c y PATENTEDJUNZU 1972 3,671,954

SHEET 20F 3 Fla-.3

I i "i o o 0 7 P PRESSURE SWITCH 1 I5b 20o V29 SLIDE VALVE 2 LOW HIGHPRESSURE PRESSURE 5 REGULATOR REGU LATO R INVENTOR:

J H Q T/EOA/G- Cua PATENTEDJUHZO 1972 3 67 1 .954

sum 3 or 3 INVENTORZ JOHN QRns11g CLA/ HTTYS.

SLAMMING INDICATOR SYSTEM FOR MARINE DEVICES The invention concernsmarine devices and has more particular reference to a means fordetecting and for indicating the incidence of slamming in ships,especially ocean-going ships.

lift from the water so as to expose the forward bottom plating of thehull, such plating being subjected to a heavy impact upon reentry. Inextreme cases the heavy impact can cause plastic deformation of theplating and sets of the order of one inch have been experienced.

I-lithertofore, the onset of slamming has been audibly detectable on thebridge and it has therefor been possible for appropriate action, say areduction in speed, to be taken before the slamming reaches suchproportions as would cause severe damage to the plating. However, inpresent day ship design, particularly of container ships, the bridge islocated aft and the length of the ship is such that no audibleindication of slamming is apparent at the bridge.

The primary object of the present invention is to provide a means fordetecting and for indicating that conditions appropriate to slammingexist.

According to the present invention a slamming indicator comprises ahollow body having an opening therein adapted to allow of a ready flowof water into and from the body, the said body being for mounting in aships bottom at .a position whereat slamming occurs and with the openingin sealed register with a through hole in the said bottom, and apressure sensing means sensitive to air pressure within the body andabove the water level therein, the said pressure sensing means beingadapted to actuate an indicator according to the pressure sensedrelative to a datum pressure.

Preferably, the pressure sensing means includes an element movablymounted within a chamber and subject to the air pressure within the saidbody, and a switch means adapted to be actuated by the said elementaccording to the position thereof.

According to a further feature of the invention the body part includes afixed stop to limit the extent of movement of the movably mountedelement.

In one arrangement the switch means will comprise a pressure actuatedelectric switch arranged to operate when subjected to a datum pressureand the movable element will be adapted to connect the said pressureactuated electric switch with the datum pressure on movement of themovable element consequent upon a pressure reduction within the hollowbody consistent with slamming.

In another arrangement the switch means will be held in an opencondition by normal air pressure present in the space between themovable element and the free water surface within the stackpipe, andwill close on a reduction of such pressure consequent upon a lifting ofthe bows of the vessel from the water.

The invention will now be described further, by way of ex ample only,with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic side elevation showing the location of theslamming indicator installation of the present invention on a containership;

FIG. 2 is a section on line IIII of FIG. I, drawn to a larger scale;

FIG. 3 is a diagrammatic representation, partly in section, of apreferred arrangement;

FIG. 3a is a fragmentary view, in section, of the slide valve 28 in ventposition for venting pressure from switch 29;

FIG. 3b is a view similar to FIG. 3a of valve 28 in position topressurize switch 29;

FIG. 4 is a view corresponding to FIG. 3 of modified arrangement; and

FIG. 4a is an enlarged fragmentary view, in section, of the arrangementfor operating directly on switch 29 with rod 27;

In severe head seas it is not unusual for the bow of a ship to FIG. 5 isa diagrammatic section of a deflection gauge as applied to a shipsbottom plate for use, in conjunction with the present invention.

Referring now to the drawing, and particularly to FIGS. 1 to 3 thereof,a slamming indicator comprises a stack pipe 11 located within the shipsdouble bottom and open to the sea through a hole 12 in the bottomplating 13, a sensing unit 14 sensitive to air pressure within the stackpipe 11, and a warning indicator 15a controlled by the said unit 14 andarranged to give a visible or audible indication at a control panel 200on the bridge, of presence within the stack pipe of an air pressureconsistent with slamming conditions existing.

The stack pipe 11 is twenty-seven inches long and of four inches insidediameter, the outer end of the stack pipe being flush with the outersurface of the hull, and the inner end of the pipe is closed by a plate16 secured transversely thereof, as by welding. A through hole 17 isprovided in the wall of the stack pipe adjacent the inner end thereof,the said hold receiving a transfer pipe 18 into engagement therewith, aninclined baffle 19 being located within the stack pipe and in closelyspaced disposition relative to the end of the transfer pipe to preventdirect passage of water into the transfer pipe on slamming. The transferpipe is of three quarter inch bore and the baffle, which baffle extendsacross the tube, is two inches wide and one quarter inch thick. Thelength of the stack pipe and the axial location of the transfer pipethereon are such that the latter lies slightly above the normal waterlevel within the stack pipe with the ship fully laden, the inclinedbaffle likewise being disposed above the water level.

The sensing unit 14 consists of a closed chamber defined by upper andlower flanged body parts 20, 21, an apertured plate 22 being arrangedtransversely of the said parts and being clamped at its peripherybetween the flanges thereof. The plate 22 divides the chamber into upperand lower chambers 23, 24, the lower such chamber being connected withthe stack pipe 11 via the transfer pipe 18 and the upper such chamberbeing connected with a source of pressure air via feed pipe 25.

A flexible diaphragm 26 is disposed transversely of the lower chamber 24and at the underside of the apertured plate 22, the periphery of thesaid diaphragm being clamped between the flange of the lower body part21 and the plate 22 and the diaphragm being secured to the stem 27 of aslide valve 28, such valve 28 controlling the passage of low pressureair into a pressure switch 29 in the electrical circuit of an in dicatorlamp of the indicator means.

Feed pipe 25 includes a high pressure regulator 30 and a low pressureregulator 31 each in series therewith, pressure gauges 32, 33 beingprovided for regulators 30, 31 respectively, and a branch 25a of thesaid feed pipe is connected with the lower chamber 24 through a gatevalve 34, the branch pipe 25a and gate valve 34, which latter isnormally closed, being provided for a purging purpose hereafter to bemade apparent.

Transfer pipe 18 has a gate valve 35 serving to isolate the sensing unit14 from the stack pipe as required, and a two-way selector valve 36 isprovided in such pipe intermediate the gate valve and chamber. Theselector valve is used for test purposes and serves to provide a meansof checking the serviceability of the equipment, by connecting the lowerchamber 24 selectively to the stack pipe 11 and to the atmosphere.Actuation of the valve 35 is by way of a handwheel control 35a operatingon the valve through an extended spindle 35b, such spindle passingthrough suitable glands 350 in the ship structure.

In use the air pressure with the stack pipe 11 is monitored, and suchpressure serves to control the pressure switch 29 and hence theenergization or otherwise of any indicator means in circuit therewith,as next to be described.

When the ships bottom leaves the water, any water within the stack pipewill be forced out by the air pressure above it and the air pressurewithin the stack pipe will fall to atmospheric, as will the pressurewithin the lower chamber 24. A pressure differential will exist at thetwo sides of the diaphragm, (the pressure within the upper chamber beingof the orderof 9 inches water gauge), and the diaphragm will movedownwardly thereby moving the stem 27 of the slide valve to putthepressure switch in communication with the source of low pressure air.The pressure switch is set to operate at the pressure of the lowpressure air, and hence the circuit of the indicator a, be it a light oraudible warning, is energized.

As the ships bottom re-enters the water, so the air within the stackpipe is compressed and the pressure rises to return the diaphragm to itsrest position against the apertured plate. The return motion of thediaphragm adjusts the slide valve and isolates the pressure switch fromthe source of low pressure air, the air within the switch being releasedto atmosphere through a bleed pipe 37 and the switch then being opened.

If it is required to purge thestack pipe of mud or other obstruction,the gate valve 34 is opened so that pressure air is fed to the stackpipe via branch pipe 25a through the lower chamber 24 to the transferpipe 18 and thence to the interior of the stack pipe.

The circuit of the indicator 15a may be provided with a counter 15b toprovide a check on the number of instances at which the bows have liftedfrom the water to expose the under plating of the hull, and appropriatemeans may be provided to ascertain and to indicate the frequency ofslamming or presence of slamming conditions The construction andoperation of the sensing unitas shown in FIG. 3 may be modified, andindeed simplified, if desired, and a modified arrangement is showndiagrammatically in F IG. 4 in which like references to those of FIG. 3are used for the same or similar parts.

In the arrangementof FIG. 4, the diaphragm of the unit 14 servesmechanically to control an electrical switch through a control rodcarried thereby, air at low pressure being applied to the underside ofthe diaphragm and to the space between such diaphragm and the watersurface within the stack pipe through line '25. The pressure within thespace will increase beyond that of the line pressure, say 8 pounds persquare inch, as the water level in the stack pipe rises and the switchwill be so arrangedas to be open at an air pressure within the spaceconsistent with the bows being in the water. The pressure at which airif fed to the space is, however, not sufl'rcient of itself to maintainthe switch in an open condition and thus a lowering of the pressure suchas would result from a lifting of the bows from the sea will close theswitch and complete the electrical circuit of the indicator 15a.

The arrangements as aforesaid are concerned with detecting andindicating the pressure of slamming conditions, and it is intended thatsuch arrangement be used as an advance warning that slamming might occurin order that appropriate preventative action might be taken to avoidslamming.

We propose to provide as a device complementary to that hereinbeforedescribed, a means of measuring the actualpermanent deformationintroduced by slamming, such means being shown diagrammatically in FIG.5, and consisting of a plate deflection gauge 41 mounted on a platform42 arranged in spaced disposition relative to the ships bottom plate 13,the deflection gauge including a spring loaded plunger 43 disposedwithin a cylindrical holder 44 carried by and extending through theplatform 42, the lower end of the plunger resting on the ships bottomplate and the upper end carrying a light rod 46 within which is embeddeda soft iron slug (not shown). The slug lies within a coil 47and ismovable axially thereof on movement of the lower end of the plungerrelative to the platform as on deformation. A switch 48 is provided onthe holder, set to be actuated upon a predetermined deflection of thebottom plate. The coil 47 forms a part of an electrical circuit whichfurther includes a meter 49 on the panel at the control point, andvariations in inductance consequent upon deformation are manifested asreadings on the meter.

' The switch 48 is set to operate upon deflection of the bottom plate toa predetermined extent, a resilient deformation giving rise to atemporary illumination of a lamp 51 in circuit with the switch and apermanent deformation resulting in the lamp being continuallyilluminated. in practice the switch is set to operate on a 6 mm.deflection. 7

Movement of the slug within the coil varies its inductance, and thechange in inductance is converted into a dc. voltage which isproportional to the linear movement of the slug.

As an alternative to using a variable inductance transducer, we mayprefer to utilize an hydraulic deflection gauge, the latter comprising aspring loaded piston in contact with the plate and moving within anhydraulic cylinder, movement of the piston displacing hydraulic fluidthrough narrow bore tubing, the displacement being indicated by amulti-tube manometer on the bridge.

The location of the stack pipe (or stack pipes) and of the platedeflection gauge (or gauges) is a matter of choice, it being understoodthat these will be in position at those parts of the hull normallysubjected to slamming, and this will vary according to the route and theprevailing winds.

For ships sailing between the United Kingdom and the East-' em seaboardof North America we have found it convenient to provide stack pipes ofthe slamming indicatoron the port side between frames 156 and 157 andbetween frames 172 and 173, whilst deflection gauges are provided on thekeel strake between frames and 171 and between frames 178 and 179, andon a strake between frames 174 and 175.

What I claim is:

1. Apparatus for automatically indicating the incidence of slamming of aship in a body of water, the apparatus including an entrance port incommunication with the sea at the ships bottom at a forward positiontherein, an air-filled chamber in said ship in communication with saidentrance port so that duringnormal sailing of the ship, sea water entersa lower portion of the chamber through said entrance port to increasethe pressure of the said air therein, while under conditions ofslamming, the sea water tends to withdraw from the said lower portionthrough said entrance port to decrease the said pressure, said chamberincluding an entrance sub-chamber located at the ships bottom incommunication with said entrance port and defining the lower portion ofsaid air-filled chamber, a measurement sub-chamber in said ship remotefrom and upwards from said entrance sub-chamber, conduit meansconnecting said entrance sub-chamber with said measurement sub-chamber,a pressure responsive device in said measurement sub-chamber responsiveto changes in pressure of the air therein incident to the occurrence ofa slamming condition, and indicating means responsive to said pressureresponsive device to actuate an alarm when the pressure falls below apredetermined value corresponding to the incidence of slamming.

2. Apparatus according to claim 1, wherein the entrance sub-chambercomprises a verticallyextending pipe of which the lower end comprisesthe entrance port and of which the upper end is connected to the saidconduit at a position which lies above the highest level that the freesurface of the sea water in the said lower portion reaches within thepipe during the said normal sailing of the ship when fully laden.

3. Apparatus according to claim 2, wherein a baffle is mounted withinthe pipe adjacent to the said connection, the baffle lying above thesaid highest level of the free surface of water and serving to tend toprevent the passage of the Sea water into the said conduit.

4. Apparatus according to claim 1, wherein the said conduit includes anON/OFF valve.

5. Apparatus according to claim 1, wherein the said conduit includes atwo-position test valve for connecting the measurement sub-chamberalternatively to the entrance sub-chamber or to the atmosphere.

6. Apparatus according to claim 1, wherein the pressureresponsive devicecomprises a movable member of which opposite sides are exposedrespectively to the air within the measurement sub-chamber and to theatmosphere within an auxiliary chamber, the movable member beingconnected to' an operating rod for operation of the indicating means.

7. Apparatus according to claim 6, wherein the auxiliary chamber isconnected to a supply of air at a constant pressure.

8. Apparatus according to claim 6, wherein the movable member is aflexible diaphragm.

9. Apparatus according to claim 7, wherein a stop is provided for thediaphragm, within the auxiliary chamber. I

10. Apparatus according to claim 6, wherein the operating rod is movableby the movable member to control the supply of air to a pressure-operated electrical switch.

11. Apparatus according to claim 6, wherein the operating rod is movableby the movable member to mechanically control the operation of anelectrical switch.

12. Apparatus according to claim 1, wherein the air-filled chamber isconnected via a nonnally closed valve to a source of air under pressure,for purging of the chamber.

13. Apparatus according to claim I, wherein the air-filled chamber ispermanently connected to a supply of air at a pressure insufiicient ofitself to prevent the said actuation of the alarm upon the incidence ofslamming.

14. Apparatus for automatically indicating the incidence of slamming ofa ship in a body of water, comprising port means located in the bottomof said ship at a forward portion thereof and in open communicationthrough the bottom of the ship with said body of water, an air-filledchamber in the ship normally in fluid communication with said portmeans, said airfilled chamber including an entrance chamber in the shipsbottom in communication with the entrance port and a measurement chamberremote from and upwards from said entrance chamber, conduit meansconnecting said entrance chamber with said measurement chamber, movablemeans in said measurement chamber responsive to changes in pressure offluid in said port means incident to the occurrence of a slammingcondition, pressure responsive switch means controlled in response tomovement of said movable means, said movable means connected with valvemeans to control the flow of air to said switch means to operate saidswitch means upon the occurrence ,of a slamming condition of said shipin said body of water, and indicating means connected with said switchmeans and controlled thereby to indicate the incidence of slamming ofsaid ship in said body of water.

15. Apparatus as in claim 14, wherein an actuating rod is connected withsaid movable means and with said switch to directly operate said switchupon movement of said movable means.

i i i l t

1. Apparatus for automatically indicating the incidence of slamming of aship in a body of water, the apparatus including an entrance port incommunication with the sea at the ship''s bottom at a forward positiontherein, an air-filled chamber in said ship in communication with saidentrance port so that during normal sailing of the ship, sea waterenters a lower portion of the chamber through said entrance port toincrease the pressure of the said air therein, while under conditions ofslamming, the sea water tends to withdraw from the said lower portionthrough said entrance port to decrease the said pressure, said chamberincluding an entrance sub-chamber located at the ship''s bottom incommunication with said entrance port and defining the lower portion ofsaid air-filled chamber, a measurement sub-chamber in said ship remotefrom and upwards from said entrance sub-chamber, conduit meansconnecting said entrance sub-chamber with said measurement sub-chamber,a pressure responsive device in said measurement sub-chamber responsiveto changes in pressure of the air therein incident to the occurrence ofa slamming condition, and indicating means responsive to said pressureresponsive device to actuate an alarm when the pressure falls below apredetermined value corresponding to the incidence of slamming. 2.Apparatus according to claim 1, wherein the entrance sub-chambercomprises a vertically extending pipe of which the lower end comprisesthe entrance port and of which the upper end is connected to the saidconduit at a position which lies above the highest level that the freesurface of the sea water in the said lower portion reaches within thepipe during the said normal sailing of the ship when fully laden. 3.Apparatus according to claim 2, wherein a baffle is mounted within thepipe adjacent to the said connection, the baffle lying above the saidhighest level of the free surface of water and serving to tend toprevent the passage of the sea water into the said conduit.
 4. Apparatusaccording to claim 1, wherein the said conduit includes an ON/OFF valve.5. Apparatus according to claim 1, wherein the said conduit includes atwo-position test valve for connecting the measurement sub-chamberalternatively to the entrance sub-chamber or to the atmosphere. 6.Apparatus according to claim 1, wherein the pressure-responsive devicecomprises a movable member of which opposite sides are exposedrespectively to the air within the measurement sub-chamber and to theatmosphere within an auxiliary chamber, the movable member beingconnected to an operating rod for operation of the indicating means. 7.Apparatus according to claim 6, wherein the auxiliary chamber isconnected to a supply of air at a constant pressure.
 8. Apparatusaccording to claim 6, wherein the movable member is a flexiblediaphragm.
 9. Apparatus according to claim 7, wherein a stop is providedfor the diaphragm, within the auxiliary chamber.
 10. Apparatus accordingto claim 6, wherein the operating rod is movable by the movable memberto control the supply of air to a pressure -operated electrical switch.11. Apparatus according to claim 6, wherein the operating rod is movableby the movable member to mechanically control the operation of anelectrical switch.
 12. Apparatus according to claim 1, wherein theair-filled chamber is connected via a normally closed valve to a sourceof air under pressure, for purging of the chamber.
 13. Apparatusaccording to claim 1, wherein the air-filled chamber is permanentlyconnected to a supply of air at a pressure insufficient of itself toprevent the said actuation of the alarm upon the incidence of slamming.14. Apparatus for automatically indicating the incidence of slamming ofa ship in a body of water, comprising port means located in the bottomof said ship at a forward portion thereof and in open communicationthrough the bottom of the ship with said body of water, an air-filledchamber in the ship normally in fluid communication with said portmeans, said air-filled chamber including an entrance chamber in theships bottom in communication with the entrance port and a measurementchamber remote from and upwards from said entrance chamber, conduitmeans connecting said entrance chamber with said measurement chamber,movable means in said measurement chamber responsive to changes inpressure of fluid in said port means incident to the occurrence of aslamming condition, pressure responsive switch means controlled inresponse to movement of said movable means, said movable means connectedwith valve means to control the flow of air to said switch means tooperate said switch means upon the occurrence of a slamming condition ofsaid ship in said body of water, and indicating means connected withsaid switch means and controlled thereby to indicate the incidence ofslamming of said ship in said body of water.
 15. Apparatus as in claim14, wherein an actuating rod is connected with said movable means andwith said switch to directly operate said switch upon movement of saidmovable means.